On Thu, Apr 1, 2021 at 8:39 PM Dan van der Ster <dan@vanderster.com> wrote:
On Wed, Mar 31, 2021 at 6:46 PM Patrick Donnelly <pdonnell@redhat.com> wrote:
Hello Yongseok,
On Wed, Mar 31, 2021 at 1:13 AM Yongseok Oh <yongseok.oh@linecorp.com>
wrote:
...
A few things I have analyzed - Rejoining process consumes a considerable amount of time. That's a known issue. (Sometimes respawning MDS happened. Increasing mds_heartbeat_grace doesn't help.)
Please turn up logging to:
debug_mds = 5
to get an idea what the MDS is doing when respawn occurs.
If it helps, here is a log with 2/5 from a recent failover which took 3.5 minutes: https://termbin.com/b022 This is 14.2.11 with the optimized recall/cache tuning.
the "Updating MDS map to version" keep showing from init-rejoin at around 2021-03-18 17:12:52.863 until 2021-03-18 17:22:36.356 while the rejoin itself finished at 2021-03-18 17:15:58.325 So,if it do associated to paxos(with too much changes between then), maybe pinning some subtree/directory to particular mds/rank would help too. Indeed rejoin is always the longest step -- even with cephfs_metadata
on SSDs. These MDSs had the cache limit set to 8GB, and you can see that the rejoining MDS needed 56GB while booting.
I haven't had a chance to test the rejoin/openfiletables optimizations yet. (https://github.com/ceph/ceph/pull/37383) But I had understood that this is intended to decrease that rejoin memory usage -- will it also speed things up?
-- dan _______________________________________________ Dev mailing list -- dev@ceph.io To unsubscribe send an email to dev-leave@ceph.io